Mixed ester O-quinone diazide photosensitizers and process of preparation

ABSTRACT

The invention relates to new mixed ester photosensitive compounds and photosensitizer compositions comprised thereof. The photosensitive compounds and photosensitizer compositions are prepared by condensing phenolic compounds with a 1,2-naphthoquinonediazide-5-sulfonic acid halide and an organic acid halide in specific ratios. Photoresist compositions comprising the photosensitive compounds and photosensitizer compositions are also disclosed. The photosensitizer compositions exhibit excellent solution stability and resistance to precipitation when formulated in alkali-soluble resin photoresist compositions. The photoresist compositions have enhanced lithographic properties.

This is a divisional of co-pending application Ser. No. 858,631 filed onMay 2, 1986, now U.S. Pat. No. 4,732,837.

BACKGROUND OF THE INVENTION The present invention relates generally tophotosensitive compositions and radiation sensitive positive photoresistcompositions and particularly to compositions containing novolak andpolyvinyl phenol resins together with naphthoquinone diazide sensitizingagents.

It is well known in the art to produce positive photoresist formulationssuch as those described in U.S. Pat. Nos. 3,666,473, 4,115,128,4,173,470 and 4,550,069. These include alkali-soluble novolak resinstogether with light-sensitive materials, usually a substitutednaphthoquinone diazide compound. The resins and sensitizers aredissolved in an organic solvent or mixture of solvents and are appliedas a thin film or coating to a substrate suitable for the particularapplication desired.

The novolak resin component of these photoresist formulations is solublein aqueous alkaline solutions, but the naphthoquinone sensitizer acts asa dissolution rate inhibitor with respect to the resin. Upon exposure ofselected areas of the coated substrate to actinic radiation, however,the sensitizer undergoes a radiation induced structural transformationand the exposed areas of the coating are rendered more soluble than theunexposed areas. This difference in solubility rates causes the exposedareas of the photoresist coating to be dissolved when the substrate isimmersed in alkaline developing solution while the unexposed areas arelargely unaffected, thus producing a positive relief pattern on thesubstrate.

In most instances, the exposed and developed substrate will be subjectedto treatment by a substrate-etchant solution. The photoresist coatingprotects the coated areas of the substrate from the etchant and thus theetchant is only able to etch the uncoated areas of the substrate, whichin the case of a positive photoresist, correspond to the areas that wereexposed to actinic radiation. Thus, an etched pattern can be created onthe substrate which corresponds to the pattern of the mask, stencil,template, etc., that was used to create selective exposure patterns onthe coated substrate prior to development.

The relief pattern of photoresist on substrate produced by the methoddescribed above is useful for various applications including, forexample, as an exposure mask or a pattern such as is employed in themanufacture of miniaturized integrated electronic components.

The properties of a photoresist composition which are important incommercial practice include the photospeed of the resist, developmentcontrast, resist resolution, and resist adhesion.

Photospeed is important for a photoresist, particularly in applicationswhere a number of exposures are needed, for example, in generatingmultiple patterns by a repeated process, or where light of reducedintensity is employed such as in projection exposure techniques wherethe light is passed through a series of lenses and mono-chromaticfilters. Thus, increased photospeed is particularly important for aresist composition employed in processes where a number of multipleexposures must be made to produce a mask or series of circuit patternson a substrate. Development contrast refers to a comparison between thepercentage of film loss in the exposed area of development with thepercentage of film loss on the unexposed area. Ordinarily, developmentof an exposed resist coated substrate is continued until the coating onthe expoeed area is substantially completely dissolved away and thus,development contrast can be determined simply by measuring thepercentage of the film coating loss in the unexposed areas when theexposed coating areas are removed entirely.

Resist resolution refers to the capability of a resist system toreproduce the smallest equally spaced line pairs and intervening spacesof a mask which is utilized during exposure with a high degree of imageedge acuity in the developed exposed spaces.

In many industrial applications, particularly in the manufacture ofminiaturized electronic components, a photoresist is required to providea high degree of resolution for very small line and space widths (on theorder of one micron or less).

The ability of a resist to reproduce very small dimensions, on the orderof a micron or less, is extremely important in the production of largescale integrated circuits on silicon chips and similar components.Circuit density on such a chip can only be increased, assumingphotolithography techniques are utilized, by increasing the resolutioncapabilities of the resist.

In order to achieve the desired sensitivity and contrast, it isnecessary to have a sufficiently high concentration of photosensitivecompounds in the photoresist to prevent dissolution of the unexposedresist during development. High concentrations photosensitizer may beachieved by dissolving a mixture of highly soluble and less solublephotosensitizers in the photoresist solution or by supersaturating thephotoresist solution with a photosensitizer.

However, solution concentration of photosensitizer near saturation canlead to a short shelf life due to solution instability and precipitationof the sensitizer prior to or during the use of the product. Thisphenomenon is referred to in U.S. Pat. Nos. 4,397,937 and 4,526,856,both of which are hereby incorporated by reference.

Clecak et al. in U.S. Pat. No. 4,397,937 discloses improved solubilityby using as a sensitizer a bisester of 1-oxo-2-diazonaphthalene sulfonicacid and an unsymmetrical primary or secondary aliphatic diol which is amixture of geometric and diastereoisomers. Esterification of thealiphatic diol at one end with a diazonaphthoquinone molecule having theacid group in the 5 position and at the other end with adiazonophthoquinone molecule having the sulfonyl group in the 4 positionis disclosed. However, the patent emphasizes the importance of limitingthe invention to unsymmetrical aliphatic diols. Clecak et al. does notdisclose mixed esters of o-quinone diazide acids and non-light-sensitiveorganic acids.

According to Lewis et al. in U.S. Pat. No. 4,526,856, the problem ofobtaining higher concentrations of sensitizer was addressed by modifyingthe solvent system of the photoresist formulations. The solventcomposition which consist of cyclopentanone, or cyclopentanone andcyclohexanone with an aliphatic alcohol, when used in certain criticalratios provides good solubility.

In contrast, the present invention provides photosensitizers which arethe condensation products of 1,2 naphthoquinonediazide-5-sulfonic acidand organic acids with aromatic diols and polyols. The photosensitizercompositions of the invention exhibit excellent solubility andresistance to precipitation when formulated in photoresist compositions.Also they may be dissolved into photoresist compositions at highersolution concentrations than previously known comparablephotosensitizers. The photoresist compositions of the invention exhibitexcellent solution stability and an improved shelf life. At the sametime they also exhibit excellent photosensitivity and contrastproperties.

SUMMARY OF THE INVENTION

The invention relates to new mixed ester photosensitive compounds andphotosensitizer compositions comprised thereof. The photosensitivecompounds and photosensitizer compositions are prepared by condensingphenolic compounds with a 1,2-naphthoquinonediazide-5-sulfonic acidhalide and an organic acid halide in specific ratios. Photoresistcompositions comprising the photosensitive compounds and photosensitizercompositions are also disclosed. The photosensitizer compositionsexhibit excellent solution stability and resistance to precipitationwhen formulated in alkali-soluble resin photoresist compositions. Thephotoresist compositions have enhanced lithographic properties.

According to the present invention there is provided: photosensitivecompounds represented by the general formulae (1), (2) or (3): ##STR1##wherein R is H, --X--R_(b) or ##STR2## X is a single C--C bond, --O--,--S--, --SO₂ --, ##STR3## n is 1 or 2, R_(a) is H, --OH, --OY, --OZ,halogen or lower alkyl, with at least one R_(a) radical being --OY andat least one thereof being --OZ, R_(b) is H, alkyl, aryl, substitutedalkyl, or substituted aryl; ##STR4## wherein R₁ is H, or , ##STR5##R_(c) is H, --OH, --OY or ##STR6## --OZ, with at least one R_(c) radicalbeing --OY and at least one thereof being --OZ; and ##STR7## wherein R₂is H, alkyl, aryl, substituted alkyl, or substituted aryl, R_(d) is--OH, --OY or --OZ with at least one R_(d) radical being --OY and atleast one thereof being --OZ; wherein Y is1,2-naphthoquinonediazide-5-sulfonyl and Z is --W--R₃, where W is##STR8## or --SO₂ --, and R₃ is alkyl, aryl, substituted alkyl orsubstituted aryl.

According to the present invention there is provided: a photosensitizercomposition comprising the condensation product of:

(I) a phenolic compound selected from the group consisting of: ##STR9##wherein R is H, --X--R_(b), or ##STR10## R_(a) is H, --OH, halogen orlower alkyl, with at least two and not greater than six R_(a) radicalsbeing --OH, X is a single C--C bond, --O--, --S--, --SO₂ --, ##STR11## nis 1 or 2, R_(b) is H, alkyl, aryl, substituted alkyl or substitutedaryl; ##STR12## wherein R₁ is H or ##STR13## R_(c) is H or --OH with atleast two R_(c) radicals being --OH; and ##STR14## wherein R₂ is H,alkyl, aryl, substituted alkyl, or substituted aryl;

(II) a 1,2-naphthoquinonediazide-5-sulfonic acid (Diazo); and

(III) an organic acid halide represented by the formula:

    W--R.sub.3

wherein W is ##STR15## or --SO₂ --V, V is halogen, R₃ is alkyl, aryl,substitted alkyl or substituted aryl;

wherein the molar ratio of the amount of Diazo reacted to the amount oforganic acid reacted is in the range of from about 1:2 to about 19:1.

According to the present invention there is provided:

a process for preparing a photosensitizer composition comprising:condensing a phenolic compound represented by the general formulae (A),(B) or (C): ##STR16## wherein R is H, --X--R_(b), or ##STR17## R_(a) isH, --OH, halogen or lower alkyl, with at least two and not greater thansix R_(a) radicals being --OH, X is a single C--C bond, --O--, --S--,--SO₂ --, ##STR18## n is 1 or 2, R_(b) is H, alkyl, aryl, substitutedalkyl or substituted aryl; ##STR19## wherein R₁ is H or ##STR20## R_(c)is H or OH with at least two R_(c) radicals being --OH; and ##STR21##wherein R₂ is H, alkyl, aryl, substituted alkyl or substituted aryl,with a 1,2-napthoquinonediazide-5-sulfonic acid (Diazo) and with anorganic acid halide represented by the formula W--R₃,

wherein W is ##STR22## or --SO₂ --V, V is halogen, R₃ is alkyl, aryl,substituted alkyl or substituted aryl; wherein the molar ratio of theamount of Diazo to the amount of organic acid halide to be reacted is inthe range of from about 1:2 to about 19:1.

According to the present invention there is provided: a photoresistcomposition comprising in admixture a novolak or polyvinyl phenol resin,a photosensitive compound as described above, and a solvent.

According to the present invention there is provided: a photoresistcomposition comprising in admixture a novolak or polyvinyl phenol resin,a photosensitizer composition as described above, and a solvent.

According to the present invention there is provided: a method forproducing an article which comprises coating a photoresist compositionas described above onto a substrate; imagewise exposing said compositionto sufficient ultraviolet radiation to render said imagewise exposedportions substantially soluble in an aqueous alkaline solution; and thenremoving the thusly exposed composition portions from said substratewith an aqueous alkaline developing solution.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

It has been found that by substituting an organic acid for a portion ofthe 1,2-naphthoquinonediazide-5-sulfonyl groups (Diazo) inphotosensitizer compositions consisting essentially of1,2-naphthoquinonediazide-5-sulfonyl esters of phenolic compounds, novelmixed ester photosensitive compounds and photosensitizer compositionsmay be obtained. These Diazo/organic acid mixed esters andphotosensitizer compositions thereof may be formulated inpositive-acting alkali-soluble novolak or polyvinyl phenol resinphotoresist compositions which exhibit excellent solution stability. Thephotoresist compositions of the invention exhibit higher contrast thancomparable heretofore available photoresist compositions and a longer"induction period" is observed when they are developed withmetal-ion-free developer solutions.

The photosensitive compounds and photosensitizer compositions may beobtained by condensing phenolic compounds with a mixture of Diazo andorganic acid halides. The molar ratio of the amount of Diazo to theamount of organic acid halide in the mixture may be in the range of fromabout 1:2 to about 19:1, preferably from about 2:3 to about 19:1 or morepreferably from about 7:8 to about 9:1. For example, one mole of2,3,4-trihydroxybenzophenone may be condensed with a mixture of 1.4moles of Diazo and 1.6 moles of methanesulfonyl chloride to yield aphotosensitizer composition comprising compounds having the formula:##STR23## where R₁, R₂ and R₃ may independently be either1,2-naphthoquinonediazide-5-sulfonyl (Diazo) or methanesulfonyl.

Thus, in one aspect, the invention provides photosensitive compoundsuseful in photosensitizer compositions. The photosensitive compounds maybe represented by general formulae (1), (2) and (3): ##STR24## wherein Ris H, --X--R_(b) or ##STR25## X is a single C--C bond, --O--, --S--,--SO₂ --, ##STR26## n is 1 or 2, R_(a) is H, --OH, --OY, --OZ, halogen,preferably Cl or Br, or lower alkyl, preferably lower alkyl having 1-4carbon atoms, with at least one R_(a) radical being --OY and at leastone thereof being --OZ, R_(b) is H, alkyl, aryl, substituted alkyl, orsubstituted aryl; preferably alkyl having 1-20 carbon atoms, morepreferably 1-12 carbon atoms, preferably aryl being phenyl or naphthyl,alkyl or aryl may be substituted with lower alkyl having 1--4 carbonatoms, lower alkoxy having 1-4 carbon atoms, or halogen, preferably Clor Br; ##STR27## wherein R₁ is H, or ##STR28## R_(c) is H, --OH, --OY or--OZ, with at least one R_(c) radical being --OY and at least onethereof being --OZ; and ##STR29## wherein R₂ is H, alkyl, aryl,substituted alkyl, or substituted aryl, the alkyl radicals R₂ may bestraight-chain or branched and may be substituted with halogen atoms orlower alkoxy groups having 1-4 carbon atoms, preferably the alkylradicals have 1-20 carbon atoms; the aryl radicals R₂ are preferablymononuclear and may be substituted with lower alkyl or alkoxy groupshaving 1-4 carbon atoms or with halogen atoms, preferably the arylradicals have 1 to 10 carbon atoms; compounds in which R₂ is an arylradical are particularly preferred and compounds in which the arylradical is a phenyl radical are especially preferred; R_(d) is --OH,--OY or --OZ with at least one R_(d) radical being --OY and at least onethereof being --OZ;

wherein Y is 1,2-naphthoquinonediazide- 5-sulfonyl and Z is --W--R₃,where W is ##STR30## or --SO₂ --, and R₃ is alkyl, aryl, substitutedalkyl or substituted aryl; the alkyl radicals R₃ may be straight-chainor branched and may be substituted with halogen atoms, preferably Br orCl, or lower alkoxy groups having 1-4 carbon atoms, preferably alkylhaving 1-20 carbon atoms; the aryl radicals R₃ are preferablymononuclear and may be substituted with lower alkyl or alkoxy groupshaving 1-4 carbon atoms or with halogen atoms, preferably Br or Cl,preferably aryl radicals having 6-10 carbon atoms; phenyl radicals arepreferred; alkyl radicals are particularly preferred and lower alkylradicals having 1-6 carbon atoms are especially preferred.

These photosensitive compounds may be prepared, for example, in themanner as herein described for the preparation of the photosensitizercompositions. The compounds may be isolated and purified as desired.

Another aspect of the invention provides photosensitizer compositionscomprising inter alia the photosensitive compounds disclosed herein. Thephotosensitizer compositions may be obtained by condensing phenoliccompounds with a mixture of Diazo and organic acid halides. The Diazocomponent and the organic acid halide component of the mixture may becondensed either sequentially or concurrently with the phenoliccompounds.

The Diazo/organic acid mixture may be reacted preferably instoichiometric quantities with the hydroxyl-bearing compounds. However,the phenolic compounds need not be completely esterified and less thanstoichiometric quantities of the Diazo and organic acid halide compoundsmay be condensed with the phenolic compounds provided that the molarratio of Diazo to organic acid halide reacted is within the rangesspecified herein. The total amount of Diazo and organic acid halidereacted with the phenolic compounds should be sufficient to produce aphotosensitizer composition capable of inhibiting the dissolution rateof an alkali-soluble resin.

The phenolic compounds which may be condensed with the Diazo/organicacid mixture are represented by the general formulae (A), (B) and (C):##STR31## wherein R is --H, --OH, --X--R_(b), or ##STR32## R_(a) is H,--OH, halogen, preferably Cl or Br, or lower alkyl, preferably loweralkyl having 1 to 4 carbon atoms; with at least two and not greater thansix R_(a) radicals being --OH, X is a single C--C bond, --O--,--S--,--SO₂ --, ##STR33## n is 1 or 2, R_(b) is H, alkyl, aryl,substituted alkyl or substituted aryl; preferably alkyl having 1-20carbon atoms, more preferably 1-12 carbon atoms, preferably aryl beingphenyl or naphthyl, alkyl or aryl may be substituted with lower alkylhaving 1-4 carbon atoms, lower alkoxy having 1-4 carbon atoms, orhalogen atoms, preferably Cl or Br; ##STR34## wherein R₁ is H or##STR35## R_(c) is H or --OH with at least two R_(c) radicals being--OH; and ##STR36## wherein R₂ is H, alkyl, aryl, substituted alkyl, orsubstituted aryl; the alkyl radicals R₂ may be straight-chain orbranched and may be substituted with halogen atoms or lower alkoxygroups having 1-4 carbon atoms, preferably the alkyl radicals have 1-20carbon atoms; the aryl radicals R₂ are preferably mononuclear and may besubstituted with lower alkyl or alkoxy groups having 1-4 carbon atoms orwith halogen atoms, preferably the aryl radicals have 1 to 10 carbonatoms; compounds in which R₂ is an aryl radical are particularlypreferred and compounds in which the aryl radical is a phenyl radicalare especially preferred.

Among the phenolic compounds represented by the general formula (I) are:hydroxyl-bearing benzene compounds such a 1,2-dihydroxybenzene,1,3-dihydroxybenzene, 1,4-dihydroxybenzene, 1,2,3-trihydroxybenzene,1,2,4-trihydroxybenzene, 1,3,5-trihydroxybenzene, and the like;dihydroxybenzophenones such as 2,2'-dihydroxybenzophenone,2,3'-dihydroxybenzophenone, 2,4dihydroxybenzophenone,2,4'-dihydroxybenzophenone, 2,5dihydroxybenzophenone,3,3'-dihydroxybenzophenone, 4,4'dihydroxybenzophenone, and the like;trihydroxybenzophenones such as 2,2',6-trihydroxybenzophenone,2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone,2,4,6-trihydroxybenzophenone, 3,4,5-trihydroxybenzophenone, and thelike; tetrahydroxybenzophenones such as2,2'3,4-tetrahydroxybenzophenone, 2,2',4,4'tetrahydroxybenzophenone,2,2'4,6'-tetrahydroxybenzophenone, 2,2',5,6'-tetrahydroxybenzophenone,2,3',4,4'-tetrahydroxybenzophenone, 2,3',4,6-tetrahydroxybenzophenone,2,4,4',6-tetrahydroxybenzophenone, 3,3',4,4',-tetrahydroxybenzophenone,and the like; pentahydroxybenzophenones; hexahydroxybenzophenones;dihydroxy- and trihydroxy- phenyl alkyl ketones such as2,4dihydroxyphenyl alkyl ketones, 2,5-dihydroxyphenyl alkyl ketones,3,4-dihydroxyphenyl alkyl ketones, 3,5-dihydroxyphenyl alkyl ketones,2,3,4-trihydroxyphenyl alkyl ketones, 3,4,5-trihydroxyphenyl alkylketones, 2,4,6-trihydroxyphenyl alkyl ketones, and the like, preferablyalkyl having 1-12 carbon atoms such as methyl, ethyl, butyl, n-hexyl,heptyl, decyl, dodecyl, and the like; dihydroxyphenyl aralkyl ketones;trihydroxyphenyl aralkyl ketones; dihydroxydiphenyls;trihydroxydiphenyls such as 2,2',4-trihydroxydiphenyl;tetrahydroxydiphenyls such as 2,2',4,4'-tetrahydroxydiphenyl;dihydroxydiphenyl oxides; dihydroxydibenzyl oxides; dihydroxydiphenylalkanes, preferably lower alkanes such as methane, ethane, propane orthe like; dihydroxybenzoic acid; trihydroxybenzoic acids; dihydroxy- andtrihydroxy- benzoic acid alkyl esters, alkyl preferably having 1 to 12carbon atoms, such as n-butyl 2,4-, 2,5-, 3,4- and3,5-dihydroxybenzoate, 2,4,4-trimethylpentyl 2,4-dihydroxybenzoate, andthe like; dihydroxy- and trihydroxy- benzoic acid phenyl esters;dihydroxy-, trihydroxy-, and tetrahydroxy- diphenyl sulfides such as4,4'-dihydroxydiphenyl sulfide; dihydroxydiphenyl sulfones; anddihydroxy- and trihydroxy- phenyl naphthyl ketones such as2,3,4-trihydroxyphenyl naphthyl ketone; and the like.

Examples of compounds of general formula (I) where at least one R_(a)radical is halogen or lower alkyl include 2,4-dihydroxy-3,5-dibromobenzophenone; 5-bromo-2,4-dihydroxybenzoic acid and esters;2,4,2',4'-tetrahydroxy-3,5,3',5'-tetrabromodiphenyl;4,4'-dihydroxy-2,2'dimethyl-5,5'-di-tert.-butyl diphenyl;4,4'-dihydroxy-2,2'dimethyl-5,5'-di-tert.-butyl diphenyl sulfide;2,4,2',4'-tetrahydroxy-3,5,3'5'-tetrabromodiphenyl sulfone; and thelike.

The preferred phenolic compounds of general formula (I) are thehydroxyl-bearing benzenes and benzophenones and the especially preferredcompounds are the trihydroxybenzophenones.

Among the phenolic compounds represented by general formula (II) are:dihydroxynaphthalenes such as 1,2-dihydroxynaphthalene,1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene,1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene,1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene,2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, and the like;dihydroxydinaphthylmethanes such as 2,2'dihydroxydinaphthylmethane, andthe like. The dihydroxynaphthylenes are preferred. The hydroxyl groupsof the dihydroxynaphthylenes may be either on the same nucleus or ondifferent nucleii of the naphthalene moiety.

Among the phenolic compounds represented by general formula (III) arebis-(3-benzoyl-4,5,6-trihydroxyphenyl)-methane;bis-(3-acetyl-4,5,6-trihydroxyphenyl)-methane;bis-(3-propionyl-4,5,6-trihydroxyphenyl)-methane;bis-(3-butyryl-4,5,6-trihydroxyphenyl)-methane;bis-(3-hexanoyl-4,5,6-trihydroxyphenyl)-methane;bis-(3-heptanoyl-4,5,6-trihydroxyphenyl)-methane;bis-(3-decanoyl-4,5,6-trihydroxyphenyl)-methane;bis-(3-octadecanoyl-4,5,6-trihydroxyphenyl)-methane; and the like.

The organic acid halides which may be used to modify the Diazo estercompounds may be represented by the formula:

    W--R.sub.3

wherein W is ##STR37## or --SO₂ --V, V is halogen, preferably Cl or Br,and R₃ is alkyl, aryl, substituted alkyl or substituted aryl; the alkylradicals R₃ may be straight-chain or branched and may be substitutedwith halogen atoms, preferably Br or Cl, or lower alkoxy groups having1-4 carbon atoms, preferably the alkyl radicals have 1-20 carbon atoms;the aryl radicals R₃ are preferably mononuclear and may be substitutedwith lower alkyl or alkoxy groups having 1-4 carbon atoms or withhalogen atoms, preferably Br or Cl, preferably the aryl radicals have 6to 10 carbon atoms, phenyl radicals are especially preferred; compoundsin which R₃ is an alkyl radical are particularly preferred and compoundsin which the alkyl radical is lower alkyl radical having 1-6 carbonatoms are especially preferred.

Among the organic acid halides represented by the above formula arealkyl sulfonyl halides such as methanesulfonyl chloride, ethanesulfonylchloride, propanesulfonyl chloride, n-butanesulfonyl chloride,dodecanesulfonyl chloride, and the like; arylsulfnyl chlorides such asbenzenesulfonyl chloride, naphthalenesulfonyl chlorides, and the like;acyl halides such as acetyl chloride, butanoyl chloride, valerylchloride, benzoyl chloride, benzoyl bromide, naphthoyl chlorides, andthe like.

The preferred organic acid halides are lower alkyl sulfonyl halides andlower alkyl acyl halides having 1-6 carbon atoms, and benzenesulfonylhalides and benzoyl halides. These acid halides may be substituted orunsubstituted.

The following examples are presented solely to illustrate the inventionand should not be considered to constitute limitations on the invention,many variations of which are possible without departing from the spiritor scope thereof.

Preparation of Photosensitizer Compositions

The preparation of naphthoquinonediazide photosensitizers is describedin U.S. Pat. Nos. 3,046,118, 3,106,645 and 4,397,937, which are herebyincorporated by reference. The photosensitizer compositions of thisinvention may be obtained by condensing the desirednaphthoquinonediazide sulfonyl halide and organic acid halide with aphenolic compound which has more than one hydroxyl group in the presenceof an acid scavenger. The resulting sensitizer composition may bepurified as desired.

Solvents for the reaction may include, but are not limited to, acetone,p-dioxane, tetrahydrofuran, methylene chloride, pyridine, or the like.

The acid scavenger may be inorganic, such as sodium carbonate, or thelike, or organic, such as sodium salts of weak acids, tertiary aminessuch as triethyl amine, pyridines, or the like.

A preparative example follows:

EXAMPLE 1

23.0 grams of 2,3,4-trihydroxybenzophenone and 37.6 grams of1,2-naphthoquinonediazide-5-sulfonyl chloride (Diazo) are stirredtogether in 165 ml acetone. 20.5 grams of methanesulfonyl chloride areadded in. 34.0 grams of triethylamine are slowly dropped in whilemaintaining an internal temperature of about 30° C. The reaction mixtureis filtered, the salt cake washed with 165 ml acetone, and the acetonesolution drowned in 2.97 liters of 1 normal hydrochloric acid. Theproduct is filtered off, washed with water, and dried in an air oven at≦40° C. The yield obtained is 67.8 grams, 99.7% of theory.

The product thusly obtained may be purified as desired.

The method of synthesis shown in this example is not the only way tomake such photosensitizer compositions, as those skilled in the art mayobtain comparable products by simply varying solvents, bases or reactionconditions. Several other examples are set forth in Table 1.

                  TABLE 1                                                         ______________________________________                                                Diazo    Diazo      Methane-  Diazo                                           Trisester                                                                              3,4 Bisester                                                                             Sulfonate Nitrogen                                Sensitizer.sub.1                                                                      (%)      (%)        Trisester (%)                                                                           (%)                                     ______________________________________                                        A       30.5     3.0        16.6      6.20                                    B       30.1     4.2        13.8      6.38                                    C       29.0     4.7        11.2      6.28                                    D       12.2     1.6        9.3       6.09                                    E       12.8     1.7        7.9       6.09                                    F       13.1     0.8        9.9       5.99                                    G       12.2     1.0        9.6       6.11                                    H       14.3     1.9        10.3      6.20                                    I       12.7     0.7        6.6       6.60                                    J       10.3     0.7        6.4       6.36                                    K       12.8     1.9        6.9       6.47                                    L       13.2     1.9        9.2       6.53                                    M       12.4     1.7        6.8       6.40                                    N       12.7     1.8        7.6       6.50                                    O       14.9     --         7.6       6.38                                    P       11.9     0.7        7.7       6.41                                    ______________________________________                                         .sup.1 Sensitizers A, B and C were prepared by reacting the Diazo with        2,3,4trihydroxybenzophenone first and then adding in the methanesulfonyl      chloride. Sensitizers M and 0 were prepared by reacting the                   methanesulfonyl chloride with 2,3,4trihydroxybenzophenone first and then      adding in the Diazo. Sensitizers D through L, N and P were prepared by        condensing the Diazo and methanesulfonyl chloride concurrently with           2,3,4trihydroxybenzophenone.                                             

EXAMPLE 2

A photosensitizer composition is prepared by condensing1,2,3trihydroxybenzene with 90 mole percent Diazo and 10 mole percentmethanesulfonyl chloride in a 1 to 3 molar ratios. 0.74 grams of theresulting sensitizer is formulated in 24.26 grams of a solutioncomprising 28.4 percent novolak resin and 71.6 percent AZ Thinner, asolvent mixture comprising cellosolve acetate, butyl acetate and xyleneavailable from American Hoechst Corporation, Somerville, N.J. Thelithographic properties are measured and it is found that at anabsorptivity of 0.740 l/g-cm at 398 nm, the photoresist has a darkerosion rate of 0.004 μm/minute, a photosensitivity of 31.0 mJ/cm²determined under 350-450nm broad band exposure measured at 405 nm, and acontrast value of 2.50. The photoresist composition remains in a stablesolution for at least two weeks when stored at room temperature. Incontrast, an unmodified photosensitizer obtained by condensing1,2,3-trihydroxybenzene with Diazo in a 1 to 3 molar ratio could not beformulated in a stable solution with the above resin and solventmixture.

Comparative Example

Comparative examples are prepared by condensing2,3,4-trihydroxybenzophenone with 1,2-naphthoquinonediazide-5-sulfonylchloride in a molar ratio of 1 to 1.4. A photosensitizer composition isobtained having diazide trisester content of about 36 to 40 by weight, a3,4-bisester content of about 18 to 20 percent by weight and a2,3,4-trihydroxybenzophenone content of about 9 to 10 percent by weight.In the following tables, this photosensitizer composition is designatedas "X".

Preparation of Positive Photoresist Systems

The photoresist composition may be prepared by formulating thephotosensitizer compositions of this invention with alkali-solubleresins, solvents and, if desired, other additives. Alkali-soluble resinswhich may be used include, for example, novolak resins, polyvinyl phenolresins, and the like.

Alkali-soluble novolak resins, which may be used for preparingphotosensitive compositions, are known in the art. A procedure for theirmanufacture is described in Chemistry and Application of PhenolicResins, Knop, A. and Scheib, W.; Springer Verlag, New York, 1979 inChapter 4 which is incorporated herein by reference.

The photoresist compositions of this invention are prepared bydissolving the above-mentioned novolak or polyvinyl phenol resins andthe photosensitizer compositions of the invention in a solvent. Suitablesolvents for this purpose include, for example, propylene glycol methylether acetate and the like; glycol ethers such as ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether and the like;cellosolve acetates such as methyl cellosolve acetate, ethyl cellosolveacetate and the like; esters such as ethyl acetate, butyl acetate andthe like; ketones such as methyl ethyl ketone, cyclopentanone,cyclohexanone and the like; and aromatic hydrocarbons such as toluene,xylene and the like. It is also possible to use mixtures thereof. Thechoice of solvent, or mixture of solvents, will depend upon the coatingmethod intended, layer thickness, drying conditions and consideration ofthe solubilities of the constituents, vaporization speed of solventafter coating the photoresist composition on a substrate, and the like.

Optionally, additives such as colorants, dyes, anti-striation agents,plasticizers, adhesion promoters, speed enhancers and such surfactantsas non-ionic surfactants may be added to the photoresist compositionbefore it is coated onto a substrate.

In the preferred embodiments, the solid parts of the photoresistcompositions, that is the novolak or polyvinyl phenol binder resin andphotosensitizer composition, preferably ranges from 15% to about 99%novolak or polyvinyl phenol binder resin and from about 1% to about 85%photosensitizer composition. A more preferred range of binder resinwould be from about 50% to about 97% and most preferably from about 65%to about 93% by weight of the solid resist parts. A more preferred rangeof photosensitizer composition would be from about 3% to about 50% andmost preferably from about 7% to about 35% by weight of the solid resistparts. In preparing the resist composition the binder resin andphotosensitizer composition are mixed with the solvent such that thesolvent is present in an amount of from about 40% to about 90% by weightof the overall resist composition. A more preferred range is from about60% to about 85% and most preferably from about 65% to about 80% byweight of the overall resist composition.

Examples of dye additives that may be used together with the photoresistcompositions of the present invention include Methyl Violet 2B (C.I. No.42535), Crystal Violet (C.I. 42555), Malachite Green (C.I. No. 42000),Victoria Blue B (C.I. 44045) and Neutral Red (C.I. No. 50040) at one toten percent weight levels, based on the combined weight of novolak andsensitizer. The dye additives help provide increased resolution byinhibiting back scattering of light off the substrate.

Anti-striation agents may be used up to five percent weight level, basedon the combined weight of novolak and sensitizer.

Plasticizers which may be used include, for example, phosphoric acidtri-(β-chloroethyl)-ester; stearic acid; dicamphor; polypropylene;acetal resins; phenoxy resins; and alkyl resins at one to ten percentweight levels, based on the combined weight of novolak and sensitizer.The plasticizer additives improved the coating properties of thematerial and enable the application of a film that is smooth and ofuniform thickness to the substrate.

Adhesion promoters which may be used include, for example,β-(3,4-epoxy-cyclohexyl)-ethyltrimethoxysilane; p-methyl-disilane-methylmethacrylate; vinyltrichlorosilane; and γ-amino-propyl triethoxysilaneup to a 4 percent weight level, based on the combined weight of novolakand sensitizer.

Speed enhancers that may be used include, for example, picric acid,nicotinic acid or nitrocinnamic acid at a weight level of up to 20percent, based on the combined weight of novolak and sensitizer. Theseenhancers tend to increase the solubility of the photoresist coating inboth the exposed and unexposed areas, and thus they are used inapplications when speed of development is the overriding considerationeven though some degree of contrast may be sacrificed; i.e., while theexposed areas of the photoresist coating will be dissolved more quicklyby the developer, the speed enhancers will also cause a larger loss ofphotoresist coating from the unexposed areas.

Non-ionic surfactants that may be used include, for example,nonylphenoxy poly(ethyleneoxy) ethanol; octylphenoxy (ethyleneoxy)ethanol; and dinonyl phenoxy poly(ethyleneoxy) ethanol at up to 10percent weight levels, based on the combined weight of novolak andsensitizer.

Solubility and Solution Stability

Photoresist compositions were prepared according to the method outlinedabove. The photosensitizer compositions from the examples are dissolvedin a prefiltered solution of resin and propylene glycol methyl etheracetate (PGMEA) or AZ Thinner solvent.

The compositions of the solutions is set forth in Table 2.

The prepared photoresist test solutions are filtered through an Alsop175 filter pad, then through a 0.2 μm Fluoropore filter (available fromMillipore Corporation). The test solutions are protected from light andstored in a constant temperature air oven at 50° C. for a period ofseven days and then examined for visible precipitate. If precipitate isvisible in a test solution, the sample has failed the solution stabilitytest. The photoresist solutions are also tested for solution stabilityat room temperature. The solutions are preiodically examined for visiblecrystallization, precipitation and color change.

                  TABLE 2                                                         ______________________________________                                                                         Diazo N.sub.2                                       Photosensitizer           Contrast                                            Composition               of Photoresist                               Example                                                                              (% weight)  Resin Solution                                                                              Composition                                  ______________________________________                                        3      9.12% A     24% novolak/76%                                                                              0.565%                                                         PGMEA                                                      4      8.86% B     24% novolak/76%                                                                             0.565%                                                          PGMEA                                                      5      9.00% C     24% novolak/76%                                                                             0.565%                                                          PGMEA                                                      6      9.29% D     24% novolak/76%                                                                             0.565%                                                          PGMEA                                                      7      9.3% E      24% novolak/76%                                                                             N/A                                                             PGMEA                                                      8      9.3% F      24% novolak/76%                                                                             N/A                                                             PGMEA                                                      9      9.3% G      24% novolak/76%                                                                             N/A                                                             PGMEA                                                      10     9.3% N      24% novolak/76%                                                                             N/A                                                             PGMEA                                                      11     9.3% O      24% novolak/76%                                                                             N/A                                                             PGMEA                                                      12     9.3% P      24% novolak/76%                                                                             N/A                                                             PGMEA                                                      13     8.825% N    25.6% novolak/                                                                              N/A                                                             74.4% AZ Thinner                                           14     8.825% O    25.6% novolak/                                                                              N/A                                                             74.4% AZ Thinner                                           15     8.825% P    25.6% novolak/                                                                              N/A                                                             74.4% AZ Thinner                                           ______________________________________                                    

The photoresist compositions of the invention have excellent solutionstability and good color. The photoresist composition of Examples 3through 15 show no visible precipitation after storage at 50° C. for oneweek. At room temperature, no visible precipitate is observed forExamples 3-10, 12, 13 and 15 after seven months. Example 11 precipitatedat four months and Example 14 precipitated at six months. The solutioncolor is exceptionally clear and light in comparison to photoresistsprepared with type X photosensitizers of the comparative examples.

The choice of the solvent system may affect the ability to formulate aparticular photosensitizer composition. For example, a photosensitizermay be difficult to formulate in one solvent system, but readilyformulated in another. However, where the modified and unmodifiedphotosensitizer compositions can be formulated, the unmodifiedcomposition will generally precipitate before the modified composition.

The solubility of the photosensitizer compositions may be tested bydissolving the photosensitizer in a solvent at various concentrationsand observing the solution over several days. A photosensitizer of typeG dissolved in acetone shows no crystallization at concentrations ashigh as 30 percent. In contrast, a photosensitizer of type Xcrystallizes overnight at 30 percent and 15 percent concentrations. Asmall amount of flocculant is observed at the 5 percent concentrationsof the type X photosensitizer.

Photosensitivity, Contrast and Unexposed Film Loss

The prepared resist solution, can be applied to a substrate by anyconventional method used in the photoresist art, including dipping,spraying, whirling and spin coating. When spin coating, for example, theresist solution can be adjusted as to the percentage of solids contentin order to provide coating of the desired thickness given the type ofspinning equipment utilized and the amount of time allowed for thespinning process. Suitable substrates include silicon, aluminum orpolymeric resins, silicon dioxide, doped silicon dioxide, siliconnitride, tantalum, copper, polysilicon, ceramics and aluminum/coppermixtures.

The photoresist coatings produced by the above described procedure areparticularly suitable for application to thermally grown silicon/silicondioxide-coated wafers such as are utilized in the production ofmicroprocessors and other miniaturized integrated circuit components. Analuminum/aluninun oxide wafer can be used as well. The substrate mayalso comprise various polymeric resins especially transparent polymerssuch as polyesters.

After the resist composition solution is coated onto the substrate, thesubstrate is baked at approximately 80° to 105° C. until substantiallyall the solvent has evaporated and only a thin coating of photoresistcomposition on the order of a micron in thickness remains on thesubstrate. The coated substrate can then be exposed to actinic radiationespecially ultraviolet radiation in any desired exposure patternproduced by use of suitable masks, negatives, stencils, templates, etc.

The exposed resist-coated substrates are next substantially immersed inalkaline developing solution. The solution is preferably agitated, forexample, by nitrogen burst agitation.

The substrates are allowed to remain in the developer until all, orsubstantially all, of the resist coating has dissolved from the exposedareas.

After removal of the coated wafers from the developing solution, apost-development heat treatment or bake may be employed to increase thecoating's adhesion and chemical resistance to etching solutions andother substances. The post-development heat treatment can comprise theoven baking of the coating and substrate below the coating's softeningpoint. In industrial applications, particularly in the manufacture ofmicrocircuitry units on silicon/silicon dioxide-type substrates, thedeveloped substrates may be treated with a buffered, hydrofluoric acidbase etching solution. The resist compositions of the present inventionare resistant to acid-base etching solutions and provide effectiveprotection for the unexposed resist-coating areas of the substrate.

The following specific examples will provide detailed illustrations ofthe methods of producing and utilizing compoitions of the presentinvention. These examples are not intended, however, to limit orrestrict the scope of the invention in any way and should not beconstrued as providing conditions, parameters or values which must beutilized exclusively in order to practice the present invention.

EXAMPLES

Resist formulations are prepared with the photosensitizer compositionsof this invention. The sensitizer to be tested is dissolved in apre-filtered stock solution of resin and solvent. The resist solutionsare then filtered. The photoresist composition are spin coated onseveral silicon wafers at a constant, predetermined spin speed to obtain2.0 μm layers of dried resist film. The wafers are then baked at 90° C.for 30 minutes.

The initial film thicknesses of the resist coatings are measured by aRudolf Film Thickness Monitor. The wafers are then exposed to variedamounts of UV light energy (350-450 nm). The resists are developed for 1minute at 25° C. using AZ 400K alkali developer, AZ alkali developer orAZ 312 MIF alkali developer, available from American HoechstCorporation, Somerville, N.J. diluted with deionized water. Theremaining film thicknesses are then remeasured by the Rudolf FilmThickness Monitor to determine film loss for the particular energy dose.Photosensitivity is measured by generating a characteristic curve, asdescribed in Wake, R. W. and Flanigan, M. C., "A Review of Contrast inPositive Photoresists", SPIE Vol. 539, Advances in Resist Technology andProcessing II (1985), p. 291, which is herein incorporated by reference,wherein film thickness loss after one minute of development is plottedagainst the logarithm of the UV exposure dose. By interpolation of thisplot to 1.0 μm film loss, the photosensitivity value in mJ/cm² isobtained. The slope of the linear portion of the plot is the contrast.

The results of photosensitivity, contrast and dark erosion rate testingof several photoresist compositions prepared with photosensitizercompositions of this invention are set forth in Table 3 and comparedwith photoresists prepared with unmodified photosensitizer compositions.

                                      TABLE 3                                     __________________________________________________________________________    Ex-                                Developer                                  am-                                                                              Photosensitizer                                                                       Resin     Absorptivity  Strength                                                                              Dark Erosion                                                                          Photosensitivity.sup.2                                                                 Con-              ple                                                                              (% weight)                                                                            Solution  (1/g-cm)                                                                             Developer.sup.1                                                                      (ratio to H.sub.2 O)                                                                  (Rate Å/min.)                                                                     (mJ/cm.sup.2)                                                                          trast             __________________________________________________________________________    16 3.9% X  30% novolak                                                                             0.741  AZ     1:1.5   40      43.1     1.48                         70% AZ Thinner                                                     17 4.9% D  30% novolak/                                                                            0.727  AZ     1:1     30      43.2     1.90                         70% AZ Thinner                                                     18 3.9% X  30% novolak/                                                                            0.745  AZ 400K                                                                              1:5     80      27.6     2.27                         70% AZ Thinner                                                     19 4.9% D  30% novolak/                                                                            0.736  AZ 400K                                                                              1:4     40      33.6     2.55                         70% AZ Thinner                                                     20 6.9% X  30% novolak/                                                                            1.30   AZ 400K                                                                              1:4     40      14.2     3.04                         70% AZ Thinner                                                     21 8.8% D  30% novolak/                                                                            1.35   AZ 400K                                                                              1:2     40      15.1     4.03                         70% AZ Thinner                                                     22 6.9% X  30% novolak/                                                                            1.30   AZ 312 MIF                                                                           1:1.5   60      26.3     2.21                         70% AZ Thinner                                                     23 6.9% X  30% novolak/                                                                            1.30   AZ 312 MIF                                                                           1:1.5   70      26.1     2.29                         70% AZ Thinner                                                     24 6.87% X 25.6% novolak/                                                                          1.31   AZ 312 MIF                                                                           1:1.5   80      24.1     2.23                         74.4% AZ Thinner                                                   25 7.16% X 30% novolak/                                                                            1.33   AZ 312 MIF                                                                           1:1.5   90      25.2     2.37                         70% AZ Thinner                                                     26 7.12% X 30% novolak/                                                                            1.31   AZ 312 MIF                                                                           1:1.5   20      38.7     2.04                         70% AZ Thinner                                                     27 7.12% X 25.6% novolak/                                                                          1.31   AZ 312 MIF                                                                           1:1.5   80      25.8     2.38                         74.4% AZ Thinner                                                   28 8.66% B 30% novolak/                                                                            1.32   AZ 312 MIF                                                                           1:1     90      21.2     4.00                         70% AZ Thinner                                                     29 8.8% D  30% novolak/                                                                            1.35   AZ 312 MIF                                                                           1:1     150     29.9     3.71                         70% AZ Thinner                                                     30 8.8% D  30% novolak/                                                                            1.35   AZ 312 MIF                                                                           1:1     50      27.5     4.18                         70% AZ Thinner                                                     31 8.82% D 25.6% novolak/                                                                          1.33   AZ 312 MIF                                                                           1:1     50      29.9     3.74                         74.4% AZ Thinner                                                   32 8.82% D 30% novolak/                                                                            1.35   AZ 312 MIF                                                                           1:1     80      27.4     4.09                         70% AZ Thinner                                                     33 8.82% D 25.6% novolak/                                                                          1.36   AZ 312 MIF                                                                           1:1     60      29.5     4.02                         74.4% AZ Thinner                                                   34 9.24% D 30% novolak/                                                                            1.32   AZ 312 MIF                                                                           1:1     60      30.6     4.42                         70% AZ Thinner                                                     35 9.24% D 30% novolak/                                                                            1.32   AZ 312 MIF                                                                           1:1     60      31.8     4.54                         70% AZ Thinner                                                     36 9.24% E 30% novolak/                                                                            1.34   AZ 312 MIF                                                                           1:1     50      31.0     4.50                         70% AZ Thinner                                                     37 9.24% F 30% novolak/                                                                            1.33   AZ 312 MIF                                                                           1:1     50      31.4     4.41                         70% AZ Thinner                                                     38 9.24% G 30% novolak/                                                                            1.32   AZ 312 MIF                                                                           1:1     60      31.5     4.57                         70% AZ Thinner                                                     39 8.82% N 24.6 novolak/                                                                           1.36   AZ 312 MIF                                                                           1:1     80      30.0     4.17                         74.4% AZ Thinner                                                   40 8.82% O 24.6% novolak/                                                                          1.35   AZ 312 MIF                                                                           1:1     90      30.9     3.89                         74.4% AZ Thinner                                                   41 8.82% P 24.6% novolak/                                                                          1.35   AZ 312 MIF                                                                           1:1     70      31.2     3.88                         74.4% AZ Thinner                                                   __________________________________________________________________________     .sup.1 AZ 400K Developer, AZ Developer and AZ 312 MIF Developer are           available from American Hoechst Corporation, Somerville, New Jersey. The      AZ 400K Developer is an aqueous inorganic alkali developer, the AZ            Developer is a buffered aqueous inorganic alkali developer, and AZ 312 MI     is a metalion-free aqueous alkali developer containing a quaternary           ammonium salt.                                                                .sup.2 The broadband exposure energy levels were measured at 365 nm.     

The data show that the photoresist compositions of the invention exhibithigher contrast values than the comparative examples at similarphotospeeds when an aqueous alkali developer is used.

An increase n the induction period of up to about 50 percent over theinduction period of the comparative examples was observed for thephotoresist compositions of the invention when a metal-ion-freedeveloper is used. The induction period is the threshold period beforewhich the exposed portions of a resist will dissolve during development.The induction period may be measured by plotting the film loss againstthe logarithm of the energy dose.

What is claimed is:
 1. A photosensitive compound represented by thegeneral formulae (1): ##STR38## wherein R is ##STR39## X is a singleC--C bond, --O--, --S--, ##STR40## n is 1 or 2, R_(a) is H, --OH, --OY,--OZ, halogen or lower alkyl, with at least one R_(a) radical being --OYand at least one thereof being --OX;wherein Y is1,2-naphthoquinonediazide-5-sulfonyl and Z is --W--R₃, where W is##STR41## or --SO₂ --, and R₃ is alkyl, aryl, substituted alkyl orsubstituted aryl; and the total amount of Diazo and organic acid halidereacted with the phenolic compound is that amount sufficient to producea photosensitizer condensate capable of inhibiting the dissolution rateof an alkali soluble resin when mixed with said resin.
 2. Aphotosensitizer comprising the condensation product of:(I) a phenoliccompound having the formula: ##STR42## wherein R is ##STR43## R_(a) isH, --OH, halogen or lower alkyl, with at least two and not greater thansix R_(a) radicals being --OH, X is a single C--C bond, --O--, --S--,--SO₂ --, ##STR44## n is 1 or 2 and (II) a1,2-naphthoquinonediazide-5-sulfonic acid (Diazo); and (III) an organicacid halide represented by the formula:

    W--R.sub.3

wherein W is ##STR45## or --SO₂ --V, V is halogen and R₃ is alkyl, aryl,substituted alkyl or substituted aryl;wherein the molar ratio of theamount of Diazo reacted to the amount of organic acid reacted is in therange of from about 1:2 to about 19:1; and the total amount of Diazo andorganic acid halide reacted with the phenolic compound is that amountsufficient to produce a photosensitizer condensate capable of inhibitingthe dissolution rate of an alkali soluble resin when mixed with saidresin.
 3. A method of preparing a photosensitizer condensatecomprising:condensing a phenolic compound represented by the generalformulae (A): ##STR46## wherein R is ##STR47## R_(a) is H, --OH, halogenlower or lower alkyl, with at least two and not greater than six R_(a)radicals being --OH, X is a single C--C bond, --O--, --S--, --SO₂ --,##STR48## n is 1 or 2; with a 1,2-naphthoquinonediazide-5-sulfonic acid(Diazo) and with an organic acid halide represented by the formulaW--R₃, wherein W is ##STR49## or --SO₂ --V, V is halogen, R₃ is alkyl,aryl, substituted alkyl or substituted aryl; wherein the molar ratio ofthe amount of Diazo to the amount of organic acid halide to be reactedis in the range of from about 1:2 to about 19:1; and the total amount ofDiazo and organic acid halide reacted with the phenolic compound is thatamount sufficient to produce a photosensitizer condensate capable ofinhibiting the dissolution rate of an alkali soluble resin when mixedwith said resin; wherein said condensing is conducted in a solventmedium in the presence of an acid scavenger; and then subsequentlyisolating said photosensitizer condensate.
 4. A photosensitizeraccording to claim 2, wherein the ratio of the amount of Diazo reactedto the amount of organic acid halide reacted is in the range of fromabout 2:3 to about 19:1.
 5. A photosensitizer according to claim 2,wherein the ratio of the amount of Diazo reacted to the amount oforganic acid halide reacted is in the range of from about 7:8 to about9:1.
 6. A photosensitizer according to claim 2, wherein the phenoliccompound is a trihydroxybenzene, a dihydroxybenzophenone, atrihydroxybenzophenone or a tetrahydroxybenzophenone; and said organicacid halide is a lower alkyl sulfonyl halide, a benzene sulfonyl halide,a lower alkyl acyl halide or a benzoyl halide.
 7. A photosensitizeraccording to claim 4, wherein the phenolic compound is atrihydroxybenzene, a dihydroxybenzophenone, a trihydroxybenzophenone ora tetrahydroxybenzophenone; and said organic acid halide is a loweralkyl sulfonyl halide, a benzene sulfonyl halide, a lower alkyl acylhalide or a benzoyl halide.
 8. A photosensitizer according to claim 5,wherein the phenolic compound is a trihydroxybenzene, adihydroxybenzophenone, a trihydroxybenzophenone or atetrahydroxybenzophenone; and said organic acid halide is a lower alkylsulfonyl halide, a benzene sulfonyl halide, a lower alkyl acyl halide ora benzoyl halide.
 9. A photosensitizer according to claim 2, wherein thephenolic compound is 2,3,4-trihydroxybenzophenone.
 10. A photosensitizeraccording to claim 4, wherein the phenolic compound is2,3,4-trihydroxybenzophenone.
 11. A photosensitizer according to claim5, wherein the phenolic compound is 2,3,4-trihydroxybenzophenone.
 12. Amethod according to claim 3, wherein said ratio of the amount of Diazoreacted to the amount of organic acid halide reacted is in the range offrom about 2:3 to about 19:1.
 13. A method according to claim 3, whereinsaid ratio of the amount of Diazo reacted to the amount of organic acidhalide reacted is in the range of from about 7:8 to about 9:1.
 14. Amethod according to claim 3, wherein the phenolic compound is atrihydroxybenzene, a dihydroxybenzophenone, a trihydroxybenzophenone ora tetrahydroxybenzophenone; and the organic acid halide is a lower alkylsulfonyl halide, a benzene sulfonyl halide, a lower alkyl acyl halide ora benzoyl halide.
 15. A method according to claim 12, wherein thephenolic compound is a trihydroxybenzene, a dihydroxybenzophenone, atrihydroxybenzophenone or a tetrahydroxybenzophenone; and the organicacid halide is a lower alkyl sulfonyl halide, a benzene sulfonyl halide,a lower alkyl acyl halide or a benzoyl halide.
 16. A method according toclaim 13, wherein the phenolic compound is a trihydroxybenzene, adihydroxybenzophenone, a trihydroxybenzophenone or atetrahydroxybenzophenone; and the organic acid halide is a lower alkylsulfonyl halide, a benzene sulfonyl halide, a lower alkyl acyl halide ora benzoyl halide.
 17. A method according to claim 3, wherein thephenolic compound is 2,3,4-trihydroxybenzophenone.
 18. A methodaccording to claim 12, wherein the phenolic compound is2,3,4-trihydroxybenzophenone.
 19. A method according to claim 13,wherein the phenolic compound is 2,3,4-trihydroxybenzophenone.